Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
AOCI Attributable to Parent, Net of Tax
Beginning balance	$ 614,719	$ 739,994	$ 746,655	$ 790,244
Holding gains (losses) arising during period, net of tax	344	67	953	(387)
Ending balance	499,507	726,904	499,507	726,904
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax
Beginning balance	(3,376)	(4,362)	(3,985)	(3,908)
Ending balance	$ (3,032)	$ (4,295)	$ (3,032)	$ (4,295)